Dynamics of free-running, pump-modulated and coupled semiconductor and solid-state lasers

The output of a laser is a high frequency propagating electromagnetic field with superior coherence and brightness compared to that emitted by thermal sources. A multitude of different types of lasers exist, which also translates into large differences in the properties of their output. Moreover, the characteristics of the electromagnetic field emitted by a laser can be influenced from the outside, e.g., by injecting an external optical field or by optical feedback. In the case of free-running solitary class-B lasers, such as semiconductor and Nd:YVO4 solid-state lasers, the phase space is two-dimensional, the dynamical variables being the population inversion and the amplitude of the electromagnetic field. The two-dimensional structure of the phase space means that no complex dynamics can be found. If a class-B laser is perturbed from its steady state, then the steady state is restored after a short transient. However, as discussed in part (i) of this Thesis, the static properties of class-B lasers, as well as their artificially or noise induced dynamics around the steady state, can be experimentally studied in order to gain insight on laser behaviour, and to determine model parameters that are not known ab initio. In this Thesis particular attention is given to the linewidth enhancement factor, which describes the coupling between the gain and the refractive index in the active material. A highly desirable attribute of an oscillator is stability, both in frequency and amplitude. Nowadays, however, instabilities in coupled lasers have become an active area of research motivated not only by the interesting complex nonlinear dynamics but also by potential applications. In part (ii) of this Thesis the complex dynamics of unidirectionally coupled, i.e., optically injected, class-B lasers is investigated. An injected optical field increases the dimensionality of the phase space to three by turning the phase of the electromagnetic field into an important variable. This has a radical effect on laser behaviour, since very complex dynamics, including chaos, can be found in a nonlinear system with three degrees of freedom. The output of the injected laser can be controlled in experiments by varying the injection rate and the frequency of the injected light. In this Thesis the dynamics of unidirectionally coupled semiconductor and Nd:YVO4 solid-state lasers is studied numerically and experimentally.

Psychological resources, their social antecedents, and association with well-being and health behaviour in early adulthood

The success of entering work life, young people s psychological resources and self-reported well-being were studied in a longitudinal setting from a life-span developmental-contextual perspective in early adulthood. The aim was to analyse how psychosocial characteristics in early childhood and adolescence predict successful entrance into work life, how this is associated with well-being, and to assess the level of psychological resources such as dispositional optimism, personal meaning of work and coping in early adulthood. The role of these and social support, in the relationship between regional factors (such as place of residence and migration), self-reported health and life satisfaction was studied. The association between a specific coping strategy, i.e. eating and drinking in a stressful situation and eating habits, was studied to demonstrate how coping is associated with health behaviour. Multivariate methods, including binary logistic regression analyses and ANOVA, were used for statistical analyses. The subjects were members of the Northern Finland 1966 Birth Cohort, which consists of all women and men born in 1966 in the two northernmost provinces of Finland (n= 12,058). The most recent follow-up, at the age of 31 years when 11,637 subjects were alive, took place in 1997-1998. The results show, first, that social resources in the childhood family and adolescence school achievement predict entrance into the labour market. Secondly, psychosocial resources were found to mediate the relationship between migration from rural to urban areas, and subjective well-being. Thirdly, psychological resources at entrance into the labour market were found to develop from early infancy on. They are, however, influenced later by work history. Fourthly, stress-related eating and drinking, as a way of coping, was found to be directly associated with unhealthy eating habits and alcohol use. Gender differences were found in psychosocial resources predicting, and being associated with success in entering the labour market. For men, the role of attitudinal and psychological factors seems to be especially important in entrance into work life and in the development of psychological resources. For women, academic attainment was more important for successfully entering work life, and lack of emotional social support was a risk factor for stress-related eating only among women. Stress-related eating and drinking habits were predicted by a long history of unemployment as well as a low level of education among both genders, but not excluding an academic degree among men. The results emphasize the role of childhood psychosocial factors in preventing long-term unemployment and in enhancing psychological well-being in early adulthood. Success in entering work life, in terms of continuous work history, plays a crucial role for well-being and the amount of psychological resources in early adulthood. The results emphasize the crucial role of enhancing psychological resources for promoting positive health behaviour and diminishing regional differences in subjective well-being.

Feeling Better, Performing Better? Holistically-Oriented Top Performance and Well-Being (HOPE) : Performance Enhancement and Its Perceived Impacts on Musicians

Most musicians choose a career in music based on their love of the art and a desire to share it with others. However, being a performing musician is highly demanding. Despite considerable evidence of the great frequency of performance-related problems (e.g. debilitating performance anxiety) among professional musicians or aspiring musicians in the current Western classical music tradition these problems are seldom discussed openly. The existing system offers musicians very little help in learning how to build sustainable performance success into their musical career. This study it is first of its kind in Finland which addresses the issue on larger scale in a systematic way. I devised the HOPE intervention (Holistically-Oriented Top Performance and Well-Being Enhancement), in order to learn how to integrate professional peak performance and a sense of personal well-being into the lives and careers of musicians. Unlike most interventions in previous research, the HOPE intervention is explicitly holistic and aims at enhancing the whole musician, not just alleviating performance anxiety. Earlier research has not in principle focused on musicians´ psychological well-being or on their subjective perceptions. The main purpose of the study is to understand the perceived impacts of the specially devised HOPE intervention on the participants and particularly in four key areas: performing, playing or singing well-being, and overall (performing, playing or singing and well-being combined). Furthermore, it is hoped that a deeper understanding of performers´ development will be gained. The research method is interdisciplinary and mainly qualitative. The primary data consist of a series of linked questionnaires (before and after the intervention) and semi-structured follow-up interviews collected during action research-oriented HOPE intervention courses for music majors in the Sibelius Academy. With the longitudinal group called Hope 1, the core data were collected during a nine month HOPE intervention course and from follow-up interviews conducted six months later in 2003-2004. The core data of Hope 1 (nine participants) are compared with the perceived impacts on fifty-three other participants in the HOPE courses during the period since their inception, 2001-2006. The focus is particularly on participants´ subjective perceptions. Results of the study suggest that the HOPE intervention is beneficial in enhancing overall performance capacity, including music performance, and a personal sense of well-being in a music university setting. The findings indicate that within all key areas significant positive changes take place between the beginning and the end of a HOPE intervention course. The longitudinal data imply that the perceived positive changes are still ongoing six months after the HOPE intervention course is finished. The biggest change takes place within the area of performing and the smallest, in participants´ perception of their playing or singing. The main impacts include reduced feelings of stress and anxiety (an enhanced sense of well-being) as well as increased sense of direction and control in one's life. Since the results of the present research gave no other reason to believe otherwise, it is to be expected that the HOPE intervention and the results of the study can be exploited in other areas of human activity as well, especially where continuous professional top performance is a prerequisite such as in business or sports. Keywords: performance enhancement, professional top performance, subjective well-being, subjective perceptions, holism, coaching, music performance anxiety, studying music, music.

Is a Majority Enough? Psychological Well-being and Its Relation to Academic and Prosocial Motivation, Self-regulation and Achievement at school

This cross-sectional study analyzed psychological well-being at school using the Self-Determination theory as a theoretical frame-work. The study explored basic psychological needs fulfillment (BPNS), academic (SRQ-A), prosocial self-regulation (SRQ-P) and motivation, and their relationship with achievement in general, special and selective education (N=786, 444 boys, 345 girls, mean age 12 yrs 8 mths). Motivation starts behavior which becomes guided by self-regulation. The perceived locus of control (PLOC) affects how self-determined this behavior will be; in other words, to what extent it is autonomously regulated. In order learn and thus to be able to accept external goals, a student has to feel emotionally safe and have sufficient ego-flexibility—all of which builds on satisfied psychological needs. In this study those conditions were explored. In addition to traditional methods Self-organizing maps (SOM), was used in order to cluster the students according to their well-being, self-regulation, motivation and achievement scores. The main impacts of this research were: a presentation of the theory based alternative of studying psychological well-being at school and usage of both the variable and person-oriented approach. In this Finnish sample the results showed that the majority of students felt well, but the well-being varied by group. Overall about for 11–15% the basic needs were deprived depending on the educational group. Age and educational group were the most effective factors; gender was important in relation to prosocial identified behavior. Although the person-oriented SOM-approach, was in a large extent confirming what was no-ticed by using comparison of the variables: the SEN groups had lower levels of basic needs fulfillment and less autonomous self-regulation, interesting deviations of that rule appeared. Some of the SEL- and GEN-group members ended up in the more unfavorable SOM-clusters, and not all SEN-group members belonged to the poorest clusters (although not to the best either). This evidence refines the well-being and self-regulation picture, and may re-direct intervention plans, and turn our focus also on students who might otherwise remain unnoticed. On the other hand, these results imply simultaneously that in special education groups the average is not the whole truth. On the basis of theoretical and empirical considerations an intervention model was sug-gested. The aim of the model was to shift amotivation or external motivation in a more intrinsic direction. According to the theoretical and empirical evidence this can be achieved first by studying the self-concept a student has, and then trying to affect both inner and environmental factors—including a consideration of the basic psychological needs. Keywords: academic self-regulation, prosocial self-regulation, basic psychological needs, moti-vation, achievement

Work-related well-being of Finnish anesthesiologists

Anesthesiologists, according to some studies, are highly stressed, die at a significantly earlier age than their colleagues and the general population,and are among the leaders in physicians' suicide records. Data are,however, sparse and contradictory. The aim of this study was to discover details of the work-related well-being of Finnish anesthesiologists. In 2004, a cross-sectional postal survey including all 550 working Finnish anesthesiologists produced a total of 328 responses (60%); 53% were men. The anesthesiologists had the greatest on-call workload among Finnish physicians. Their average in-hospital on-call period lasted 24 hours (range 14 to 38). Over two-thirds felt stressed. The most important causes of stress were work and combining work with family. Their main worries at work were: excessive workload and time constraints, especially being on call, organizational problems, and fear of harming patients. On-call workload correlated with burnout. Being frequently on call was correlated with severe stress symptoms--symptoms associated with sick leaves. Women were more affected by stress than men. High job control and organizational justice seemed to mitigate hospital-on-call stress symptoms. The respondents enjoyed fairly high job and life satisfaction. Job control and organizational justice were the most important correlates of these wellness indicators. Work-related factors were more important in males, whereas family life played a larger role in the well-being of female anesthesiologists. Women had less job control, fewer permanent job contracts, and a higher domestic workload. Of the respondents, 31% were willing to consider changing to another physician's specialty and 43% to a profession other than medicine. The most important correlates for these job turnover attitudes were conflicts at the workplace, low job control, organizational injustice, stress, and job dissatisfaction. One in four had at some time considered suicide. Respondents with poor health, low social support, and family problems were at the highest risk for suicidality. The highest risks at work were conflicts with co-workers and superiors, on-call-related stress symptoms, and low organizational justice. If a respondent had several risk factors, the risk for suicidality doubled with each additional factor. On-call work-burden, job control, fairness of decision-making procedures,and workplace relationships should be the focus in attempts to increase the work-related well-being of anesthesiologists.

Interatomic potentials for fusion reactor material simulations

Fusion energy is a clean and safe solution for the intricate question of how to produce non-polluting and sustainable energy for the constantly growing population. The fusion process does not result in any harmful waste or green-house gases, since small amounts of helium is the only bi-product that is produced when using the hydrogen isotopes deuterium and tritium as fuel. Moreover, deuterium is abundant in seawater and tritium can be bred from lithium, a common metal in the Earth's crust, rendering the fuel reservoirs practically bottomless. Due to its enormous mass, the Sun has been able to utilize fusion as its main energy source ever since it was born. But here on Earth, we must find other means to achieve the same. Inertial fusion involving powerful lasers and thermonuclear fusion employing extreme temperatures are examples of successful methods. However, these have yet to produce more energy than they consume. In thermonuclear fusion, the fuel is held inside a tokamak, which is a doughnut-shaped chamber with strong magnets wrapped around it. Once the fuel is heated up, it is controlled with the help of these magnets, since the required temperatures (over 100 million degrees C) will separate the electrons from the nuclei, forming a plasma. Once the fusion reactions occur, excess binding energy is released as energetic neutrons, which are absorbed in water in order to produce steam that runs turbines. Keeping the power losses from the plasma low, thus allowing for a high number of reactions, is a challenge. Another challenge is related to the reactor materials, since the confinement of the plasma particles is not perfect, resulting in particle bombardment of the reactor walls and structures. Material erosion and activation as well as plasma contamination are expected. Adding to this, the high energy neutrons will cause radiation damage in the materials, causing, for instance, swelling and embrittlement. In this thesis, the behaviour of a material situated in a fusion reactor was studied using molecular dynamics simulations. Simulations of processes in the next generation fusion reactor ITER include the reactor materials beryllium, carbon and tungsten as well as the plasma hydrogen isotopes. This means that interaction models, {\it i.e. interatomic potentials}, for this complicated quaternary system are needed. The task of finding such potentials is nonetheless nearly at its end, since models for the beryllium-carbon-hydrogen interactions were constructed in this thesis and as a continuation of that work, a beryllium-tungsten model is under development. These potentials are combinable with the earlier tungsten-carbon-hydrogen ones. The potentials were used to explain the chemical sputtering of beryllium due to deuterium plasma exposure. During experiments, a large fraction of the sputtered beryllium atoms were observed to be released as BeD molecules, and the simulations identified the swift chemical sputtering mechanism, previously not believed to be important in metals, as the underlying mechanism. Radiation damage in the reactor structural materials vanadium, iron and iron chromium, as well as in the wall material tungsten and the mixed alloy tungsten carbide, was also studied in this thesis. Interatomic potentials for vanadium, tungsten and iron were modified to be better suited for simulating collision cascades that are formed during particle irradiation, and the potential features affecting the resulting primary damage were identified. Including the often neglected electronic effects in the simulations was also shown to have an impact on the damage. With proper tuning of the electron-phonon interaction strength, experimentally measured quantities related to ion-beam mixing in iron could be reproduced. The damage in tungsten carbide alloys showed elemental asymmetry, as the major part of the damage consisted of carbon defects. On the other hand, modelling the damage in the iron chromium alloy, essentially representing steel, showed that small additions of chromium do not noticeably affect the primary damage in iron. Since a complete assessment of the response of a material in a future full-scale fusion reactor is not achievable using only experimental techniques, molecular dynamics simulations are of vital help. This thesis has not only provided insight into complicated reactor processes and improved current methods, but also offered tools for further simulations. It is therefore an important step towards making fusion energy more than a future goal.

Growing Up Vietnamese in Finland - Looking Back 12 Years Later : The Well-Being and Sociocultural Adaptation of Vietnamese as Children or Adolescents and as Young Adults

Varttuminen vietnamilaisena Suomessa: 12 vuoden seurantajakso – Vietnamilaisten hyvinvointi ja sosiokulttuurinen sopeutuminen lapsena/nuorena sekä nuorena aikuisena Tämä tutkimus oli määrällinen pitkittäistutkimus lapsena tai nuorena vuosina 1979-1991 Suomeen saapuneiden vietnamilaisten akkulturaatiosta (kulttuurin muutoksista), psyykkisestä hyvinvoinnista ja sosiokulttuurisesta sopeutumisesta. Tutkimukseen osallistui ensimmäisessä vaiheessa (vuonna 1992) 97 satunnaisesti valittua vietnamilaista peruskoululaista ympäri maata, joita verrattin suomalaisiin luokkatovereihin. Seurantavaiheeseen (vuonna 2004) osallistui 59 ensimmäisessä vaiheessa mukana ollutta vietnamilaista, nyt iältään 20 – 31 -vuotiaita. Tutkimuksen tavoitteena oli selvittää mitkä tekijät ennustivat akkulturaation lopputuloksia, samalla huomioiden iän ja ympäristön (kontekstin) vaikutukset psyykkiseen hyvinvointiin ja sosiokulttuuriseen sopeutumiseen. Yksittäiset akkulturaatiodimensiot (kieli, arvot ja identiteetti) osoittautuivat tärkeämmiksi psyykkiselle hyvinvoinnille ja sosiokulttuuriselle sopeutumiselle kuin etniset, kansalliset tai kaksikulttuuriset profiilit, joissa yhdistyivät ao. kieli, arvot ja identiteetti. Identiteettimuutosta tapahtui (etniseen) vietnamilaiseen suuntaan ajan kuluessa, kun taas arvomuutosta tapahtui (kansalliseen) suomalaiseen suuntaan. Sekä suomen että vietnamin kielen taito lisääntyivät ajan myötä, millä oli myönteisiä vaikutuksia sekä psyykkiseen hyvinvointiin että sosiokulttuuriseen sopeutumiseen. Lähtötilanteen psyykkinen hyvinvointi ennusti hyvinvointia (masennuksen puutetta ja itsetuntoa) aikuisena, mutta sosiokulttuurinen sopeutuminen (koulumenestys) lapsena tai nuorena ei ennustanut kouluttautumista aikuisena. Parempi suomen kielen taito ja vähemmän identifioitumista suomalaiseksi aikuisena sekä masentuneisuuden puute ja vähemmän koettua syrjintää lapsena tai nuorena erottelivat psyykkisesti paremmin voivat aikuiset (ei-masentuneet) heistä, jotka olivat masentuneita. Parempaa kouluttautumista aikuisena ennustivat toisaalta vähemmän koettua syrjintää lapsena tai nuorena ja toisaalta aikuisena parempi suomen kielen taito, suurempi kansallisten (suomalaisten) itsenäisyysarvojen kannattaminen, mutta kuitenkin vähemmän identifioitumista suomalaisiin. Koetun syrjinnän merkitys psyykkiselle hyvinvoinnille, erityisesti lapsena tai nuorena, sekä sen pitkäaikaisvaikutukset psyykkiselle hyvinvoinnille ja sosiokulttuuriselle sopeutumiselle aikuisena osoittavat tarpeen puuttua varhain psyykkisiin ongelmiin sekä parantaa etnisten ryhmien välisiä suhteita. Avainsanat: akkulturaatio, psyykkinen hyvinvointi, sosiokultuurinen sopeutuminen, kieli, arvot, identiteetti, vietnamilainen, Suomi, lapset, nuoret, nuoret aikuiset

Retirement Transition and Well-being : A 16-year Longitudinal Study

The ageing of the labour force and falling employment rates have forced policy makers in industrialized countries to find means of increasing the well-being of older workers and of lengthening their work careers. The main objective of this thesis was to study longitudinally how health, functional capacity, subjective well-being, and lifestyle change as people grow older, and what effect retirement has on these factors and on their relationships. The present study is a follow-up questionnaire study of Finnish municipal workers, conducted in 1981 to 1997 at the Finnish Institute of Occupational Health. In 1981, a postal questionnaire was sent to 7344 municipal workers in different parts of Finland. The respondents were born between 1923 and 1937. A total of 6257 persons responded to the first questionnaire. In the end, a total of 3817 persons had responded to all four (1981, 1985, 1992, 1997) questionnaires. (The response rate was 69% of the living participants). Cross-tabulations, comparison of means, logistic regression analyses and general linear models with repeated measures were used to derive the results. The transition from work life to retirement, and the following years as a pensioner were associated with many changes. Involvement in various activities increased during the transition stage but later decreased to the previous level. Physical exercise was an exception: it became increasingly popular over the years. Perceived health improved markedly from the working stage to the retirement transition stage, even though morbidity increased steadily during the follow-up. On the other hand, functional capacity decreased over the follow-up, especially among those who were occupationally active until the retirement stage. Subjective well-being remained stable during the follow-up period. There were, however, great differences based on the type of work, favouring those whose work had been mental in nature. The impact of activity level on maintaining well-being became greater during the follow-up, whereas the effect of physical functioning diminished. Good physical functioning and an active life-style contributed to staying on at work until normal retirement age. Also work-related factors, i.e. possibilities for development and influence at work, responsibility for others, meaningful work, and satisfaction with working time arrangements were positively related to continuing working. The transition from work to retirement had a positive impact on a person s health and functional capacity. The study results support the view that it should be possible to ease one s work pace during the last years of a work career. This might lower the threshold between work and retirement and convince people that there will still be time to enjoy retirement also a few years later.

Phylogenetic analyses reveal high levels of polyphyly among pleurocarpous lineages as well as novel clades

Phylogenetic analyses of the Hypnales usually show the same picture of poorly resolved trees with a large number of polyphyletic taxa and low support for the few reconstructed clades. One odd clade, however, consisting of three genera that are currently treated either within the Leskeaceae (Miyabea) or Neckeraceae (Homaliadelphus and Bissetia), was retrieved in a previously published phylogeny based on chloroplast rbcL. In order to elucidate the reliability of the observed Homaliadelphus - Miyabea - Bissetia - clade (HMB-clade) and to reveal its phylogenetic relationships a molecular study based on a representative set of hypnalean taxa was performed. Sequence data from all three genomes, namely the ITS1 and 2 (nuclear), the trnS-rps4-trnT-trnL-trnF cluster (plastid), the nad5 intron (mitochondrial), were analyzed. Although the phylogenetic reconstruction of the combined data set was not fully resolved regarding the backbone it clearly indicated the polyphyletic nature of various hypnalean families, such as the Leskeaceae, Hypnaceae, Hylocomiaceae, Neckeraceae, Leptodontaceae and Anomodontaceae with respect to the included taxa. In addition the results favor the inclusion of the Leptodontaceae and Thamnobryaceae in the Neckeraceae. The maximally supported HMB-clade consisting of the three genera Homaliadelphus (2-3 species), Miyabea (3 species) and Bissetia (1 species) is resolved sister to a so far unnamed clade comprising Taxiphyllum aomoriense, Glossadelphus ogatae and Leptopterigynandrum. The well-resolved and supported HMB-clade, here formally described as the Miyabeaceae, fam. nov. is additionally supported by morphological characters such as strongly incrassate, porose leaf cells, a relatively weak and diffuse costa and the presence of dwarf males. The latter are absent in the Neckeraceae and the Leskeaceae. It is essentially an East Asian family, with one species occurring in North America.